<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
   <button type="button" class="intro demo">点我消失</button>

    <script src="js/jquery-3.7.1.min.js"></script>
    <!-- <script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script> -->
    

    <script>
        // $(selector).action()

        // $(document).ready(function () {
        //     $('button').click(function () {
        //         $(this).hide();
        //     });
        // });

        $("button").click(function(){
            alert("哈哈哈哈哈");
        });

    </script>
</body>
</html>